
.big_box{
margin-left: 100px;
margin-top: 50px;
height: 280px;
/* width: 400%; */
position: relative;
}
.big_box ul{
    /* width: 600%; */
   position: absolute;
    top: 0;
    left: 0;
    white-space: nowrap;
    margin: 0;
    padding: 0;
    font-size: 0;
}
.big_box ul li{
    width: 520px;
    height: 280px;
    /* margin-top: 10px;
    margin-left:20px; */
    display: inline-block;
    list-style: none;
   
}

a{
   
    text-decoration: none;
}
.focus{
    position: relative;

}
.focus_l,
.focus_r{
   
    position: absolute; 
    background-color: rgba(0, 0, 0, .7);
    color: #fff;
    width: 20px;
   height: 30px;
   text-align: center;
    line-height: 30px;
    top:50%;
   
    margin-top: -15px; 
    display: none;
    z-index: 9999;
}
.focus_l{
    border-top-right-radius: 15px;
    border-bottom-right-radius: 15px;
    left: 40px;
    top:146px;
}
.focus_r{
    right: 605px;
    top: 143px;
    border-top-left-radius: 15px;
    border-bottom-left-radius: 15px;
}
ol{
    position: absolute;
    top:245px;
       left: 200px;
}
ol li{
  
    list-style: none;
    float: left;
       width: 8px;
       height: 8px;
        background-color: #fff;
        border-radius: 50%;
       margin: 3px;
    
    
}
ol .selected{
    background-color: #ff5000;
}